Recently, as a mobile telephone has been popularized, communication of a driver during driving has been problematic. In consideration of this problem, the communication using a mobile telephone during driving is legally prohibited, but many drivers do not observe the law. As a method for solving such a problem, an invention for automatically switching a mobile telephone registered previously to a message recording mode when it is detected that a user is driving a vehicle has been applied for patent (for example, see Patent Document 1). In addition, an invention for generating distributing wave in a vehicle so as to prevent communication in a vehicle is applied (for example, see Patent Document 2).
However, in the conventional methods, communication of a fellow passenger as well as communication of the driver may be suppressed. The communication of only the driver in the vehicle need be suppressed and the communication of the fellow passenger need not be suppressed. In addition, when a driver whose mobile telephone number is registered sits on a passenger seat, the communication of the driver's telephone need not be suppressed.
[Patent Document 1] JP-A-2001-197556
[Patent Document 2] WO 01/08328